1. Field of the Invention
The present invention relates to a roller for feeding, conveying, and/or separating paper (hereinafter referred to as a “paper feed/convey/separation roller”) which is employed in a paper-feeding apparatus of various printers such as an ink-jet printer and a laser printer; various office automation (OA) apparatuses such as a copier and a facsimile; an automatic teller machine; etc., and which has at least one function among paper feeding, paper conveying, and paper separating, and to a method for producing the roller.
2. Background Art
Generally, a belt or a roller for conveying paper money, film, magnetic cards, and the like in an automatic ticket gate, an automatic teller machine, a money changer, and the like must be designed in consideration of wear resistance, oil-swell resistance, environmental impact, etc. Particularly, paper feed/convey/separation rollers for use in various OA machines must have excellent conveying capacity and high wear resistance. Therefore, EPDM (ethylene propylene diene monomer rubber) has been conventionally employed as a material for rollers having high mechanical strength and high friction coefficient.
OA machines of recent years can be operated for a long period and are employed for high-speed operation. Under such conditions, EPDM is not a satisfactory material for rollers, since sufficient wear resistance fails to be attained, which is problematic. From the viewpoint of excellent wear resistance, studies are underway on use of urethane material for producing a paper feed/convey/separation rollers. Furthermore, there have been proposed rollers employing the characteristics of different types of rubber; for example, a roller having an outer layer made of non-foamed urethane or a like material, and an inner layer made of a foamed material (see, for example, Patent Documents 1 and 2).
However, in production of the roller disclosed in Patent Document 1, an inner layer must be fixed to an outer layer by the mediation of an adhesive. The roller disclosed in Patent Document 2 is produced by molding an inner layer with an outer layer through vulcanization without use of an adhesive. However, bonding effect is insufficient, and the two layers slip with respect to each other in long-term use, thereby failing to gain sufficient running torque. Thus, these rollers have problems.
Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 1994-80269
Patent Document 2: Japanese Patent Application Laid-Open (kokai) No. 1996-211774